The blaze scorched 3½ square miles (9 square kilometers) of chaparral bush and shrub oak in the small town of Bishop on the eastern slopes of the Sierra Nevada that is popular for hiking, fishing, climbing and hunting. Firefighters made some gains against the flames, which they found had burned a slightly smaller area after doing more accurate mapping.

It comes as California has seen some record-high temperatures and little rain after emerging from a five-year drought, helping fuel some of the deadliest and most destructive wildfires in state history late last year. U.S. drought monitors this month declared parts of Southern California back in severe drought.

In the most recent fire, several communities and campgrounds in the Pleasant Valley Reservoir area were ordered to leave and persistent winds were expected to pose a challenge, said Cathey Mattingly, spokeswoman for the California Department of Forestry and Fire Protection.

It’s not clear how many people had to evacuate after the blaze started Sunday, Inyo County sheriff’s spokeswoman Carma Roper said. But at least 500 structures were threatened, including the Laws Railroad Museum, a railroad station built in the 1880s, Mattingly said.

She said at least 400 firefighters are working to contain the flames north of Bishop, a former mining town of about 3,800 that still celebrates mules each year with country music concerts, mule chariot races, log skidding and parades.

The fire broke out shortly Sunday afternoon near the Pleasant Valley Reservoir and quickly grew to 900 acres. It forced the closure of a highway that connects rural Inyo County to Nevada.